Question
Physics Question on laws of motion
A truck is moving on a friction less surface with uniform velocity of 10m/s . A leak occurs in the water tank of the truck at the rate of 2kg/s . What is the speed of truck after 50s if the mass of truck is 100kg and mass of water in the truck initially was 100kg ?
A
20m/s
B
10m/s
C
5m/s
D
None of these
Answer
None of these
Explanation
Solution
Given that, u=10m/s, dtdm=2kg/s
Total mass of the truck,
M=(100+100)kg=200kg
We know that,
F=dtudm
or F=10×2=20N
or Ma=20N
or 200a=20N
or a=20020m/s2
=101m/s2
Now, we know that,
a=tv−u [u=10m/s,t=50s]
⇒101=50v−10
⇒v=15m/s